[libc] Extend add_object rule to handle helper object libraries.

The rule is now called add_object_library.

Reviewers: abrachet

Differential Revision: https://reviews.llvm.org/D76826

Author: Siva Chandra Reddy

libc/cmake/modules/LLVMLibCRules.cmake

@@ -94,32 +94,35 @@ function(add_gen_header target_name)
   )
 endfunction(add_gen_header)
 
-set(SINGLE_OBJECT_TARGET_TYPE "LIBC_SINGLE_OBJECT")
+set(OBJECT_LIBRARY_TARGET_TYPE "OBJECT_LIBRARY")
 
-# Function to generate single object file.
+# Rule which is essentially a wrapper over add_library to compile a set of
+# sources to object files.
 # Usage:
-#     add_object(
+#     add_object_library(
 #       <target_name>
-#       SRC <source file to compile>
+#       HDRS <list of header files>
+#       SRCS <list of source files>
 #       DEPENDS <list of dependencies>
 #       COMPILE_OPTIONS <optional list of special compile options for this target>
-function(add_object target_name)
+function(add_object_library target_name)
   cmake_parse_arguments(
     "ADD_OBJECT"
     "" # No option arguments
-    "SRC" # Single value arguments
-    "COMPILE_OPTIONS;DEPENDS" # Multivalue arguments
+    "" # Single value arguments
+    "SRCS;HDRS;COMPILE_OPTIONS;DEPENDS" # Multivalue arguments
     ${ARGN}
   )
 
-  if(NOT ADD_OBJECT_SRC)
-    message(FATAL_ERROR "'add_object' rules requires a SRC to be specified.")
+  if(NOT ADD_OBJECT_SRCS)
+    message(FATAL_ERROR "'add_object_library' rule requires SRCS to be specified.")
   endif()
 
   add_library(
     ${target_name}
     OBJECT
-    ${ADD_OBJECT_SRC}
+    ${ADD_OBJECT_SRCS}
+    ${ADD_OBJECT_HDRS}
   )
   target_include_directories(
     ${target_name}
@@ -132,19 +135,33 @@ function(add_object target_name)
       PRIVATE ${ADD_OBJECT_COMPILE_OPTIONS}
     )
   endif()
+
+  set(all_object_files $<TARGET_OBJECTS:${target_name}>)
   if(ADD_OBJECT_DEPENDS)
     add_dependencies(
       ${target_name}
       ${ADD_OBJECT_DEPENDS}
     )
+    foreach(obj_target IN LISTS ADD_ENTRYPOINT_OBJ_SPECIAL_OBJECTS)
+      get_target_property(obj_type ${obj_target} "TARGET_TYPE")
+      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})))
+        continue()
+      endif()
+      # If a dependency is also a object file library, we will collect the list of
+      # object files from it.
+      get_target_property(obj_files ${obj_target} "OBJECT_FILES")
+      list(APPEND all_object_files ${obj_files})
+    endforeach(obj_target)
   endif()
+  list(REMOVE_DUPLICATES all_object_files)
+
   set_target_properties(
     ${target_name}
     PROPERTIES
-      "TARGET_TYPE" ${SINGLE_OBJECT_TARGET_TYPE}
-      "OBJECT_FILE" $<TARGET_OBJECTS:${target_name}>
+      "TARGET_TYPE" ${OBJECT_LIBRARY_TARGET_TYPE}
+      "OBJECT_FILES" "${all_object_files}"
   )
-endfunction(add_object)
+endfunction(add_object_library)
 
 set(ENTRYPOINT_OBJ_TARGET_TYPE "ENTRYPOINT_OBJ")
 
@@ -165,7 +182,7 @@ function(add_entrypoint_object target_name)
     "ADD_ENTRYPOINT_OBJ"
     "REDIRECTED" # Optional argument
     "NAME" # Single value arguments
-    "SRCS;HDRS;SPECIAL_OBJECTS;DEPENDS;COMPILE_OPTIONS"  # Multi value arguments
+    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS"  # Multi value arguments
     ${ARGN}
   )
   if(NOT ADD_ENTRYPOINT_OBJ_SRCS)
@@ -203,12 +220,34 @@ function(add_entrypoint_object target_name)
     ${target_name}_objects
     support_common_h
   )
+  set(dep_objects "")
   if(ADD_ENTRYPOINT_OBJ_DEPENDS)
     add_dependencies(
       ${target_name}_objects
       ${ADD_ENTRYPOINT_OBJ_DEPENDS}
     )
+    foreach(dep_target IN LISTS ADD_ENTRYPOINT_OBJ_DEPENDS)
+      if(NOT TARGET ${dep_target})
+        # Not all targets will be visible. So, we will ignore those which aren't
+        # visible yet.
+        continue()
+      endif()
+      get_target_property(obj_type ${dep_target} "TARGET_TYPE")
+      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})))
+        # Even from among the visible targets, we will collect object files
+        # only from add_object_library targets.
+        continue()
+      endif()
+      # Calling get_target_property requires that the target be visible at this
+      # point. For object library dependencies, this is a reasonable requirement.
+      # We can revisit this in future if we need cases which break under this
+      # requirement.
+      get_target_property(obj_files ${dep_target} "OBJECT_FILES")
+      list(APPEND dep_objects ${obj_files})
+    endforeach(dep_target)
   endif()
+  list(REMOVE_DUPLICATES dep_objects)
+
   if(ADD_ENTRYPOINT_OBJ_COMPILE_OPTIONS)
     target_compile_options(
       ${target_name}_objects
@@ -220,16 +259,6 @@ function(add_entrypoint_object target_name)
   set(object_file "${CMAKE_CURRENT_BINARY_DIR}/${target_name}.o")
 
   set(input_objects $<TARGET_OBJECTS:${target_name}_objects>)
-  if(ADD_ENTRYPOINT_OBJ_SPECIAL_OBJECTS)
-    foreach(obj_target IN LISTS ADD_ENTRYPOINT_OBJ_SPECIAL_OBJECTS)
-      get_target_property(obj_type ${obj_target} "TARGET_TYPE")
-      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${SINGLE_OBJECT_TARGET_TYPE})))
-        message(FATAL_ERROR "Unexpected target type for 'SPECIAL_OBJECT' - should be a target introduced by the `add_object` rule.")
-      endif()
-      list(APPEND input_objects $<TARGET_OBJECTS:${obj_target}>)
-    endforeach(obj_target)
-  endif()
-
   add_custom_command(
     OUTPUT ${object_file_raw}
     DEPENDS ${input_objects}
@@ -253,12 +282,16 @@ function(add_entrypoint_object target_name)
     ALL
     DEPENDS ${object_file}
   )
+  set(all_objects ${object_file})
+  list(APPEND all_objects ${dep_objects})
+  set(all_objects_raw ${object_file_raw})
+  list(APPEND all_objects_raw ${dep_objects})
   set_target_properties(
     ${target_name}
     PROPERTIES
       "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
-      "OBJECT_FILE" ${object_file}
-      "OBJECT_FILE_RAW" ${object_file_raw}
+      "OBJECT_FILES" "${all_objects}"
+      "OBJECT_FILES_RAW" "${all_objects_raw}"
   )
 endfunction(add_entrypoint_object)
 
@@ -282,13 +315,13 @@ function(add_entrypoint_library target_name)
   set(obj_list "")
   foreach(dep IN LISTS ENTRYPOINT_LIBRARY_DEPENDS)
     get_target_property(dep_type ${dep} "TARGET_TYPE")
-    string(COMPARE EQUAL ${dep_type} ${ENTRYPOINT_OBJ_TARGET_TYPE} dep_is_entrypoint)
-    if(NOT dep_is_entrypoint)
+    if(NOT (${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE}))
       message(FATAL_ERROR "Dependency '${dep}' of 'add_entrypoint_collection' is not an 'add_entrypoint_object' target.")
     endif()
-    get_target_property(target_obj_file ${dep} "OBJECT_FILE")
-    list(APPEND obj_list "${target_obj_file}")
+    get_target_property(target_obj_files ${dep} "OBJECT_FILES")
+    list(APPEND obj_list "${target_obj_files}")
   endforeach(dep)
+  list(REMOVE_DUPLICATES obj_list)
 
   set(library_file "${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}${target_name}${CMAKE_STATIC_LIBRARY_SUFFIX}")
   add_custom_command(
@@ -396,17 +429,17 @@ function(add_libc_unittest target_name)
   set(library_deps "")
   foreach(dep IN LISTS LIBC_UNITTEST_DEPENDS)
     get_target_property(dep_type ${dep} "TARGET_TYPE")
-    if (dep_type)
-      string(COMPARE EQUAL ${dep_type} ${ENTRYPOINT_OBJ_TARGET_TYPE} dep_is_entrypoint)
-      if(dep_is_entrypoint)
-        get_target_property(obj_file ${dep} "OBJECT_FILE_RAW")
-        list(APPEND library_deps ${obj_file})
-        continue()
-      endif()
+    if(${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE})
+      get_target_property(obj_files ${dep} "OBJECT_FILES_RAW")
+      list(APPEND library_deps ${obj_files})
+    elseif(${dep_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})
+      get_target_property(obj_files ${dep} "OBJECT_FILES")
+      list(APPEND library_deps ${obj_files})
     endif()
     # TODO: Check if the dep is a normal CMake library target. If yes, then add it
     # to the list of library_deps.
   endforeach(dep)
+  list(REMOVE_DUPLICATES library_deps)
 
   add_executable(
     ${target_name}
@@ -488,7 +521,7 @@ function(add_libc_fuzzer target_name)
     if (dep_type)
       string(COMPARE EQUAL ${dep_type} ${ENTRYPOINT_OBJ_TARGET_TYPE} dep_is_entrypoint)
       if(dep_is_entrypoint)
-        get_target_property(obj_file ${dep} "OBJECT_FILE_RAW")
+        get_target_property(obj_file ${dep} "OBJECT_FILES_RAW")
         list(APPEND library_deps ${obj_file})
         continue()
       endif()

libc/loader/linux/CMakeLists.txt

@@ -6,9 +6,9 @@ function(add_loader_object name)
     "DEPENDS;COMPILE_OPTIONS" # Multi value arguments
     ${ARGN}
   )
-  add_object(
+  add_object_library(
     ${name}_object
-    SRC ${ADD_LOADER_OBJECT_SRC}
+    SRCS ${ADD_LOADER_OBJECT_SRC}
     DEPENDS ${ADD_LOADER_OBJECT_DEPENDS}
     COMPILE_OPTIONS ${ADD_LOADER_OBJECT_COMPILE_OPTIONS}
   )
@@ -27,7 +27,7 @@ function(add_loader_object name)
     ${name}
     PROPERTIES
       "TARGET_TYPE" "LOADER_OBJECT"
-      "OBJECT_FILE" ${objfile}
+      "OBJECT_FILES" ${objfile}
   )
 endfunction()
 

libc/src/signal/linux/CMakeLists.txt

@@ -12,9 +12,9 @@ add_entrypoint_object(
     signal_h
 )
 
-add_object(
+add_object_library(
   __restore
-  SRC
+  SRCS
     __restore.cpp
   COMPILE_OPTIONS
     -fomit-frame-pointer
@@ -41,8 +41,6 @@ add_entrypoint_object(
     sys_syscall_h
     linux_syscall_h
     signal_h
-  SPECIAL_OBJECTS
-    __restore
 )
 
 add_entrypoint_object(

libc/test/loader/CMakeLists.txt

@@ -32,7 +32,7 @@ function(add_loader_test target_name)
   if(ADD_LOADER_TEST_DEPENDS)
     add_dependencies(${target_name} ${ADD_LOADER_TEST_DEPENDS})
     foreach(dep IN LISTS ADD_LOADER_TEST_DEPENDS)
-      get_target_property(objfile ${dep} "OBJECT_FILE")
+      get_target_property(objfile ${dep} "OBJECT_FILES")
       if(NOT objfile)
         message(
             FATAL_ERROR

libc/test/src/signal/CMakeLists.txt

@@ -23,7 +23,6 @@ add_libc_unittest(
     signal_h
     errno_h
     __errno_location
-    __restore
 )
 
 add_libc_unittest(